1. Field of the Invention
The present invention relates to heat exchangers and more particularly to a threaded cryostat for use with cryosurgical probe systems.
2. Description of the Related Art
Cryosurgical probe systems presently being manufactured by present assignee, Endocare, Inc., use high pressure gas that is introduced to a cryostat that utilizes a finned tube helical coil heat exchanger for pre-cooling the high pressure gas prior to its introduction through a Joule-Thompson nozzle. This type of heat exchanger is disclosed in, for example, U.S. Pat. No. 6,074,412, entitled “Cryoprobe,” issued to Mikus et al. Pre-cooling the incoming gas allows the cryosurgical probe to obtain lower temperatures.
U.S. Pat. No. 3,800,552, entitled “Cryogenic Surgical Instrument,” issued to Sollami et al also discloses fin-tube heat exchanger in a cryosurgical probe system. The fins disclosed are individually attached fins such as discs or plates, or a continuous helically wound fin secured to the tube.
Generally, the prior art designs for these cryostats that have attached fins are relatively expensive to implement due to the somewhat complex manufacturing requirements. Furthermore, the bonding interface between the fins and the tube to which they are bonded provides a somewhat interrupted thermally conductive path.
What is desired is a cryosurgical probe in which the cryostat is relatively simple to manufacture yet still provides the heat exchange efficiency desired for proper operation.